Identification, characterization and interaction of HAP family genes in rice

Abstract

A HAP complex, which consists of three subunits, namely HAP2 (also called NF-YA or CBF-B), HAP3 (NF-YB/CBF-A) and HAP5 (NF-YC/CBF-C), binds to CCAAT sequences in a promoter to control the expression of target genes. We identified 10 HAP2 genes, 11 HAP3 genes and 7 HAP5 genes in the rice genome. All the three HAP family genes encode a protein with a conserved domain in each family and various non-conserved regions in both length and amino acid sequence. These genes showed various expression patterns depending on genes, and various combinations of overlapped expression of the HAP2, HAP3 and HAP5 genes were observed. Furthermore, protein interaction analyses showed interaction of OsHAP3A, a ubiquitously expressed HAP3 subunit of rice, with specific members of HAP5. These results indicate that the formation of specific complex with various HAP subunits combinations can be achieved by both tissue specific expression of three subunit genes and specific interaction of three subunit proteins. This may suggest that the HAP complexes may control various aspects of rice growth and development through tissue specific expression and complex formation of three subunit members.

OsNF-YC2 and OsNF-YC4 proteins inhibit flowering under long-day conditions in rice

“…2, 3; Tables 1, 2). Our conclusion is supported by three OsNF-YC and three OsNF-YB proteins that are clustered in the same phylogenetic clade (Thirumurugan et al 2008;Petroni et al 2012;Laloum et al 2013) as AtNF-YC3/-YC4/-YC9 proteins and AtNF-YB2/-YB3 proteins, which are known to influence flowering (Kumimoto et al 2008, 19 2010). However, the possibility that the OsNF-YC subunits interact with other OsNF-YB subunits in other developmental processes, cannot be excluded.…”

“…OsNF-YB11 (rice AtNF-YB2 and AtNF-YB3 homologs) functions in the control of heading date in rice (Wei et al 2010;Yan et al 2011). Five OsNF-YC proteins (OsNF-YC1, OsNF-YC2, OsNF-YC4, OsNF-YC6 and OsNF-YC7) and three OsNF-YB proteins (OsNF-YB8, OsNF-YB10 and OsNF-YB11) of rice were identified as AtNF-YC3/4/9 and AtNF-YB2/3 homologous proteins, respectively (Thirumurugan et al 2008). We tested if these rice proteins are functional homologs to Arabidopsis counterparts.…”

“…6), and the report of Thirumurugan et al (2008) that OsNF-YB2, which is involved in chloroplast biogenesis (Miyoshi et al 2003), interacts with OsNF-YC subunits in yeast. OsNF-YC4-RNAi and OsNF-YC6-RNAi plants could be due to the functional redundancy of these genes with the homologous OsNF-YC genes (Thirumurugan et al 2008;Petroni et al 2012;Laloum et al 2013). Transgenic plants over-expressing the OsNF-YC genes showed either delayed or accelerated flowering only under LD conditions ( Fig.…”

“…Overlapping expression patterns of OsNF-YA, OsNF-YB and OsNF-YC genes have been reported (Thirumurugan et al 2008). Recently, it has been reported that the OsNF-YB11 (OsHAP3H/Ghd8/DTH8) gene is involved in the regulation of flowering time and other traits such as grain productivity and plant height (Wei et al 2010;Yan et al 2011).…”

“…In addition, Ghd7/OsI [encoding a CCT domain-containing protein (Griffiths et al 2003)] regulates flowering under LD conditions (Xue et al 2008). Although protein-protein interactions between some subsets of OsNF-YA/OsHAP2 or OsNF-YB/OsHAP3 and OsNF-YC/OsHAP5 were reported in yeast (Thirumurugan et al 2008), the interactions between OsNF-Y proteins and rice CO homologues such as Heading date 1(Hd1) have not been established. In wheat (Triticum aestivum), CO2 (a rice Hd1 homolog) and flowering repressor VRN2 (ZCCT1 and 2) are shown to compete for interactions with TaNF-Y complexes to integrate the vernalization and photoperiodic signals .…”